The present disclosure relates to a simulator for evaluating the damage sustained by a workpiece when a given process is performed on the workpiece, a processing system having the same, damage evaluation method and damage evaluation program.
If a process such as etching, PVD (Physical Vapor Deposition) or ion implantation is performed on a film to be processed in the device manufacturing process, the processed film is damaged (e.g., crystal defects in the processed film) by ion injection. It has been indicated that this damage significantly affects the electrical characteristics of the device. As a result, it has become an important challenge for the device manufacturers to solve this problem immediately.
However, it is difficult to directly measure a real pattern of damage distribution with measuring devices available today. In order to consider in detail the relation between the condition of ion injection during the process and the electrical characteristics of the device, countermeasures against the above problem and other factors, and improve the electrical characteristics of the device, therefore, it is necessary to develop a damage distribution prediction technique (evaluation technique) using simulation.
In related art, therefore, a variety of simulation techniques have been proposed that can evaluate the condition when ions are injected into a target film (refer, for example, to Japanese Patent Laid-Open Nos. Hei 7-115071 and 2010-232594 (hereinafter referred to as Patent Documents 1 and 2, respectively), J. F. Ziegler, J. P. Biersack and U. Littmark: “The Stopping and Range of Ions in Solids,” Pergamon Press, New York, 1985 (Non-Patent Document 1, hereinafter) and Kawase and Hamaguchi: Dry Process Symposium 2005 (Non-Patent Document 2, hereinafter)).
Patent Document 1 proposes an ion implantation simulation technique, and Non-Patent Document 1 an SRIM (Stopping and Range of Ions in Matter) simulation technique. These simulation techniques allow, for example, for prediction of the ion penetration depth in a target film having an amorphous structure. However, it is difficult for these techniques to quantitatively express crystal defects (e.g., crystal lattice disorder in polysilicon or silicon oxide) that occur as a result of ion penetration in consideration of the crystal structure of the target film.
Non-Patent Document 2 proposes a simulation technique using a molecular dynamics simulator. This simulation technique can predict a crystal lattice disorder in atomic or molecular level, for example, according to the incident ion energy, incidence angle, target film type and so on in consideration of interaction between incident ions and atoms making up the target film.
With the simulation technique proposed in Non-Patent Document 2, however, the amount of calculations is enormous, resulting in an extremely long calculation time. For example, if the damage distribution is calculated by applying this simulation technique to a real pattern, it is only possible to calculate the damage distribution of an extremely limited area sized about several nm by several nm in a practical calculation time (e.g., within about several weeks). Further, this simulation technique leads to an even longer calculation time if the incident ion mass is small (e.g., hydrogen ion) because of a long flying distance of the incident ions in the film. In practically calculating the damage distribution of a target film using a molecular dynamics simulator, therefore, the damage distribution of the target film is calculated by ignoring the processing pattern and assuming that the target film is flat due to these calculation time restrictions.
On the other hand, Patent Document 2 proposes a technique as an extension of the simulation technique described in Non-Patent Document 2. More specifically, the damage distribution of a workpiece is found in advance under a variety of conditions by calculating the behavior of incident particles (ion particles) in the film based on molecular dynamics, followed by preparation of a database in which the found damage distribution data is stored. In practically predicting a real pattern of damage distribution by simulation, the position of collision of the incident particles onto the workpiece and the incidence angle are calculated first using the Monte Carlo method in consideration of the transportation route in the real pattern of the incident particles. Next, the database is searched based on the calculated position of collision of the incident particles and the incidence angle to find the corresponding damage distribution. This technique eliminates the need to perform molecular dynamics calculations every simulation run, thus contributing to reduced calculation time.